Abstract

Objective

The gut microbiome is a complex community of microorganisms that inhabit the gastrointestinal tract. The microbiota–gut–brain axis encompasses a bidirectional communication system that allows the gut to influence the brain via neural, endocrine, immune, and metabolic signaling. Differences in the gut microbiome have been associated with psychiatric and neurological disorders, including Alzheimer’s Disease (ad). Understanding these ad-associated alterations may offer novel insight into the pathology and treatment of ad.

Method

We conducted a narrative review of clinical studies investigating the gut microbiome in ad, organizing the results by phyla to understand the biological contributions of the gut microbial community to ad pathology and clinical features. We also reviewed randomized clinical trials of interventions targeting the microbiome to ameliorate ad symptoms and biomarkers.

Results

Alpha diversity is reduced in patients with ad. Within Firmicutes, taxa that produce beneficial metabolites are reduced in ad, including Clostridiaceae, Lachnospiraceae, Ruminococcus, and Eubacterium. Within Bacteroidetes, findings were mixed, with studies showing either reduced or increased abundance of Bacteroides in mild cognitive impairment or ad patients. Proteobacteria that produce toxins tend to be increased in ad patients, including Escherichia/Shigella. A Mediterranean-ketogenic dietary intervention significantly increased beneficial short-chain fatty acids and taxa that were inversely correlated with changes in ad pathological markers. Probiotic supplementation with Lactobacillus spp. and Bifidobacterium spp. improved cognitive function and reduced inflammatory and metabolic markers in patients with ad.

Conclusions

The gut microbiome may provide insight into ad pathology and be a novel target for intervention. Potential therapeutics include probiotics and dietary intervention.

中文翻译：

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阿尔茨海默病中的微生物群-肠-脑轴：对分类学改变和潜在干预途径的回顾

摘要

客观的

肠道微生物群是栖息在胃肠道中的复杂微生物群落。微生物群-肠-脑轴包含一个双向通讯系统，允许肠道通过神经、内分泌、免疫和代谢信号传导影响大脑。肠道微生物组的差异与包括阿尔茨海默病在内的精神和神经系统疾病有关。了解这些与广告相关的变化可能会为广告的病理学和治疗提供新的见解。

方法

我们对广告中肠道微生物组的临床研究进行了叙述性回顾，按门组织结果以了解肠道微生物群落对广告病理学和临床特征的生物学贡献。我们还回顾了针对微生物组以改善广告症状和生物标志物的干预措施的随机临床试验。

结果

ad患者的 Alpha 多样性降低。在厚壁菌门中，产生有益代谢物的类群在ad中减少，包括梭菌科、毛螺菌科、瘤胃球菌和真杆菌。在拟杆菌门中，研究结果喜忧参半，研究显示轻度认知障碍或广告患者中拟杆菌的丰度减少或增加。在广告患者中，产生毒素的变形菌往往会增加，包括大肠杆菌/志贺氏菌。地中海生酮饮食干预显着增加了有益的短链脂肪酸和类群，它们与广告病理标志物。用乳酸杆菌属补充益生菌。和双歧杆菌属。改善了ad患者的认知功能并减少了炎症和代谢标志物。

结论

肠道微生物组可以提供对广告病理学的洞察，并成为干预的新目标。潜在的治疗方法包括益生菌和饮食干预。